Prop is slightly loose-96' Ski Nautique |
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2tall
Groupie Joined: November-10-2015 Location: MT Status: Offline Points: 47 |
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Posted: June-24-2016 at 6:01pm |
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At a slower speed at the back of the boat I heard a sort of loose click sound like maybe the cotter pins on the swim platform were loose and hitting just slightly against the metal brackets that hold the swim platform on...so I got under there after trailering it and found that the prop is just slightly loose. I can move it just barely back and forth and it seems to be causing a loose rattle noise. It still has the cotter pin on the castle nut, but the castle nut is not super tight. I can't tighten the castle nut any more because then the cotter pin would not fit in the slot (the whole purpose of the castle nut).
So can I add a spacer just before the castle nut? I only need something super thin maybe less than 1 mm Or maybe a different castle nut with more slots? ..any ideas? |
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2Tall - 1996 Ski Nautique GT-40
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41040 |
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The prop wasn't installed properly. It needs to be lapped to the shaft. The prop nut is there to seat the prop to the shaft and then a safety as you found out.
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MrMcD
Grand Poobah Joined: January-28-2014 Location: Folsom, CA Status: Online Points: 3610 |
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Do a search on this forum for lapping the prop to your shaft. It only takes about a half hour to do but is very important to a safe installation.
As far as locating the cotter Pin you could add a washer under the nut but the lapping process is what holds your prop to the shaft so don't skip that part. |
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41040 |
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41040 |
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Not needed. Seat the prop with the nut after lapping and then back the nut off to the closest slot for the cotter. |
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2tall
Groupie Joined: November-10-2015 Location: MT Status: Offline Points: 47 |
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So it seems to me the prop was maybe seated almost correctly at some point, but came loose and the person before me backed off the castle nut just as you suggested to fit the cotter key, but the real problem was the propeller was never lapped properly or maybe not tightened enough with the nut when they installed it? Am I getting the picture?
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2Tall - 1996 Ski Nautique GT-40
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41040 |
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JD,
With a lapped taper, it doesn't take much force to seat two components together. If the prop/shaft was lapped and then the two seated, you can remove the nut!!! I've seen it where the prop nut is gone, likely for some time and the prop is still there. Prop pullers are made for a reason! |
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DrCC
Grand Poobah Joined: April-12-2004 Location: at home Status: Offline Points: 2867 |
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It could also be a result of too much lapping. Removing material from the prop bore allowing the prop to move further up the shaft taper.
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41040 |
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Al, Please note that there is no mention of running out of threads but rather the nut can't be tightened anymore so the cotter pin can be inserted in the hole. I have experienced props where the prop shop has re reamed a bad bore on a prop and then yes, a washer is needed behind the nut but that's due to no threads left and not from multiple lapping. |
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MrMcD
Grand Poobah Joined: January-28-2014 Location: Folsom, CA Status: Online Points: 3610 |
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Torque specs for a 1" shaft propeller nut are listed from 30-50 foot lbs. I would feel better leaving the nut tight as the manufacturer recommends, although I fully recognize the value of proper seating of the prop to the shaft.
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peter1234
Grand Poobah Joined: February-03-2008 Location: United States Status: Offline Points: 2756 |
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when i used the napa valve lapping compound on my skylark i was amazed at how much material seemed to come off the prop. it took as said above about 30 minutes to remove an awful lot of play.
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former skylark owner now a formula but I cant let this place go
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41040 |
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Mark, I agree that there's certainly a "piece of mind" with a tight prop nut but am also glad you understand the taper principle. |
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SNobsessed
Grand Poobah Joined: October-21-2007 Location: IA Status: Offline Points: 7102 |
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Isn't it possible for the key to bind & prevent the tapers from mating? |
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“Beer is proof that God loves us and wants us to be happy.”
Ben Franklin |
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MrMcD
Grand Poobah Joined: January-28-2014 Location: Folsom, CA Status: Online Points: 3610 |
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I watched a You Tube video that showed how to check the Prop fit with and without the key installed. Basically install the prop with no key and mark where it seats on the shaft.
Next install the prop with the key installed and it should seat at exactly the same spot if not the key or keyway needs to be file fitted so it allows the prop to seat properly. It helped when I installed mine last year. Until this forum taught me proper prop installation I had never lapped one in in 30 years of boat ownership. Once learned the process makes perfect sense. |
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eric lavine
Grand Poobah Joined: August-13-2006 Location: United States Status: Offline Points: 13413 |
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Pete, really? 30000 posts???????
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"the things you own will start to own you"
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gun-driver
Grand Poobah Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4117 |
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Holy crap
WELCOME BACK ERIC |
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41040 |
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Eric,
Where have you been?? Fill us in. |
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2tall
Groupie Joined: November-10-2015 Location: MT Status: Offline Points: 47 |
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So I went and bought the Prussian Blue and the grease mix grinding compound.
I got the propeller off (easily, it was already loose) and rubbed a thin layer of the Prussion Blue around the shaft as suggested. It looked perfectly smooth. There apparently were not any high or low spots. Is that possible? I did this about 5 times with varying degrees of Blue on the shaft just to be sure and each time I see the same result. The Prussian Blue is perfectly distributed on the shaft and there appear to be no high/low points. So I cleaned off the Blue, put the key and the propeller back on, and tightened the castle nut. Then I backed off the nut just barely and pulled on the prop (by hand) and it is on there nice and tight I could not move it. So does this mean the shaft was in excellent shape and I don;t really need to do anything more? That is what it seems like to me. I inspected the length of the entire shaft and it looks brand new all the way to the motor. No scratches, no nicks or marks and it shines bright. it must be new? So how did the propeller come loose? Maybe it wasn't tight enough previously? |
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2Tall - 1996 Ski Nautique GT-40
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Hollywood
Moderator Group Joined: February-04-2004 Location: Twin Lakes, WI Status: Offline Points: 13512 |
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http://www.correctcraftfan.com/forum/forum_posts.asp?TID=38425&PN=1&title=whens-it-gonna-happen |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 10753 |
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The tranny man is still number 3 on the all time hit list behind TRB and ahead of Hollywood in spite of being away for years I think he might have passed Pete by now if he stuck around |
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backfoot100
Platinum Member Joined: January-03-2007 Location: United States Status: Offline Points: 1897 |
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If the key wasn't properly seated between the shaft and prop keyways the prop itself will never seat onto the taper. |
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When people run down to the lake to see what's making that noise, you've succeeded.
Eddie |
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63 Skier
Grand Poobah Joined: October-06-2006 Location: Concord, NH Status: Offline Points: 4246 |
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Eric, nice to see you stop by. Please let us know what you are up to, you've been missed! |
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'63 American Skier - '98 Sport Nautique
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